/*小屏幕手机端*/
@media (min-width:0px) and (max-width:768px) {
  #board {
    opacity: 0.5;
    height: 300px;
  }

  #info_zone {
    height: 75px;
  }

  .middle {
    width: 300px;
  }
}

/*中等屏幕，桌面显示器，大于等于992px*/
@media (min-width:768px) and (max-width:992px) {
  #board {
    opacity: 0.5;
    height: 400px;
  }
  
  #info_zone {
    height: 100px;
  }
  
  .middle {
    width: 400px;
  }
}

/*大屏设备*/
@media (min-width:992px) {
  #board {
    opacity: 0.5;
    height: 500px;
  }

  #info_zone {
    height: 125px;
  }

  .middle {
    width: 500px;
  }
}

.cell {
  margin: 0.25%;
  border: 4px;
  border-radius: 10%;
  border-style: solid;
  border-color: gray;
  height: 100%;
  width: 22.5%;
  float: left;
}

.row {
  margin: 2.5% 2.5% 0 0;
  width: inherit;
  height: 25%;
}

/*子元素在父元素中居中，center类为父元素*/
.center {
  display: flex;
  align-items: center;
  justify-content: center;
}

/*提示容器,居右*/
#alert-container {
  position: fixed;
  left: 20px;
  top: 20px;
}

/*消子提示*/
.alert {
  background-color: #ffffff;
  padding: 10px;
  margin-top: 10px;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
}

.alert-normal {
  color: #000000;
}

.alert-former {
  color: red;
}

.alert-later {
  color: cyan;
}


